The invention relates to the field of dimmable operating devices for light sources, specifically to dimmable operating devices for the combined operation of gas discharge lamps and semiconductor light sources.
Until now, each light source has been considered individually in the case of luminaires which also use semiconductor light sources such as light-emitting diodes in addition to the gas discharge lamps which have long been used. In the case of dimmable luminaires, each light source can be dimmed individually, but both light sources are not considered to be one unit.
U.S. Pat. No. 7,052,157 B1 has disclosed a luminaire in which LEDs are also used in addition to compact fluorescent lamps. The light sources can be dimmed independently of one another. A common dimming mechanism in which both types of light source are used is not described here.
Although fluorescent lamps can be dimmed with a corresponding degree of technical complexity down to 1% of the nominal light, the efficiency is reduced considerably at these low dimming settings. The color locus of the emitted light can also change since, at very low powers, the lamp cools down to a significant extent and it gives more weight to the argon discharge in comparison with the mercury discharge.
It is therefore desirable to provide a light source which can be dimmed more effectively, such as a semiconductor light source, for example, for very low dimming settings. In order to keep the complexity of the driving of the two light sources low, it is expedient to operate both light sources using one operating device.